The goal of RC2 is to evaluate the effectiveness of two approaches to treating periodontal disease in American Indians (Als) with diabetes. Both diabetes and periodontal disease (PD) are more than twice as common in AI/ANs than in the general U.S. population. When compared with other groups with diabetes, at least some groups of Als also experience disparities in the severity of PD. Finally, previous studies suggest that there are systemic links between the two conditions. The specific aims of this study will be: 1) to compare the efficacy of scaling and root planing (SRP) for reducing periodontal pocket depth in diabetics with scaling and root planing plus topical minocycline hydrochloride (SRP+), with both also compared to a delayed treatment control condition (TxD);2) to compare the three treatment conditions on additional measures of PD;3) to compare the three conditions on measures of glycated hemoglobin (HbA1c) and costeffectiveness; and 4) to assess safety and acceptability of the treatments. Community participation has, and will continue, to shape the design of the study and related dissemination activities. Al individuals with diabetes will be recruited through an IMS Service Unit currently participating in the Special Diabetes Program for Indians and that also includes six dental clinics. These individuals will be screened for severity of periodontal disease and invited to be further considered for participation in the study. After complete periodontal examinations and application of other inclusion and exclusion criteria, participants will be randomly assigned to conditions. The SRP and SRP+ groups will receive treatment at baseline and 3 months, and the TxD group will receive the SRP+ treatment at 6 months. All participants will be examined at baseline, 3 months, and 6 months. Recruitment of participants and treatment will continue until 540 individuals have completed the study protocol. The study participants and examiners will be blinded to treatment condition. Individuals from the participant communities and Al health service providers will be involved in the development of final protocols and procedures, as well as dissemination activities. Differences in responses of participants to treatment will be examined in terms of a set of moderator and mediator variables that will include sociodemographic data, knowledge, attitudes, and behaviors, psychological variables, and comorbidities. Structured as a Phase 3 clinical trial, this study will provide necessary information to make definitive recommendations about the preferred PD treatment for Al patients with diabetes and concurrent PD. These recommendations will take into consideration costs and other factors. Based on HbA1c analyses, the study also may provide critical information for determining next steps in the investigation of the relationship between PD and diabetes control.